mail/fetchmail: update to 6.4.28

BREAKING CHANGES:

• Bump wolfSSL minimum required version to 5.1.1 to pull in security fix.

FIXES:

• When using wolfSSL 5.0.0, work around a bug that appears to hit wolfSSL when receiving handshake records while still in SSL_peek(). Workaround is to read 1 byte and cache it, then call SSL_peek() again. This affects only some servers. https://github.com/wolfSSL/wolfssl/issues/4593

TRANSLATIONS: language translations were updated by this fine people:

• es: Cristian Othón Martínez Vera [Spanish]
• ro: Remus-Gabriel Chelu [Romanian]
• sr: Мирослав Николић (Miroslav Nikolić) [Serbian]

MFH: 2022Q1